Re: [HACKERS] LONG

> >
> > >     The  solution  I see is to give any out of line datum another
> > >     Oid, that is  part  of  it's  header  and  stamped  into  the
> > >     reference  data.  That way, the long attribute lookup can use
> > >     SnapshotAny using this  Oid,  there  can  only  be  one  that
> > >     exists,  so SnapshotAny is safe here and forces that only the
> > >     visibility of the master tuple in the main  table  counts  at
> > >     all.
> >
> > This is a great idea.  Get rid of my use of the attribute number.  Make
> > the varlena long value be:
> >
> >    long-bit|length|longrelid|longoid|longlen
> >
> > No need for attno in there anymore.
> 
>     I  still  need  it  to  explicitly  remove  one long value on
>     update, while the other one is untouched. Otherwise  I  would
>     have  to  drop  all  long  values  for  the  row together and
>     reinsert all new ones.

I am suggesting the longoid is not the oid of the primary or long*
table, but a unque id we assigned just to number all parts of the long*
tuple.  I thought that's what your oid was for.

> 
> > Having a separate oid for the long value is great.  You can then have
> > multiple versions of the long attribute in the long table and can
> > control when updating a tuple.
> >
> > I liked Hiroshi's idea of allowing long values in an index by just
> > pointing to the long table.  Seems that would work too.  varlena access
> > routines make that possible.
> 
>     Maybe possible, but not that good IMHO. Would  cause  another
>     index  scan from inside index scan to get at the value. An we
>     all agree that indexing huge values isn't that a  good  thing
>     at all.

May as well.  I can't think of a better solution for indexing when you
have long values.  I don't think we want long* versions of indexes.

--  Bruce Momjian                        |  http://www.op.net/~candle maillist@candle.pha.pa.us            |  (610)
853-3000+  If your life is a hard drive,     |  830 Blythe Avenue +  Christ can be your backup.        |  Drexel Hill,
Pennsylvania19026